Apparatus for etching a glass substrate

ABSTRACT

In an apparatus for etching a glass substrate according to the present invention, impurities that are attached to the surface of a glass substrate, which are formed by assembling a color filter substrate and a TFT substrate provided in the etching bath filled with etchant, are removed by using ultrasonic oscillation generated from an ultrasonic oscillator, by which a glass substrate having uniform thickness and surface is obtained.

[0001] This application is a continuation-in-part of U.S. applicationSer. No. 09/039,438, entitled “Etching Apparatus,” filed Mar. 16, 1998,which is related to, and incorporates by reference, U.S. applicationSer. No. 09/002,037, entitled “Method of Fabricating a Substrate,” filedDec. 31, 1997. This application also claims the benefit of KoreaApplication No. 1999-14632 filed on Apr. 23, 1999. The entirety of boththe parent U.S. Applications and the priority Korean Application areincorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an etching apparatus, and moreparticularly, to an apparatus for etching a substrate uniformly by usingultrasonic oscillation.

[0004] 2. Description of the Related Art

[0005] As a display device for a television and a personal computer, alarge sized cathode ray tube (CRT) display device is commonly used.However, since the screen must be separated from the electron gun bymore than a predetermined distance for a large size screen CRT, thevolume of the device is increased. Thus, such a CRT cannot be applied toa low weight, small size, and a low power consumption electronic device,such as a wall-mountable television, a portable television, and anotebook computer.

[0006] For a small and light display device, flat panel devices such asa liquid crystal display device (LCD), plasma display panel (PDP),electroluminescent display (ELD) and vacuum fluorescent display (VFD)have been introduced recently. Among the above flat panel displaydevices, the LCD has been researched extensively for good picturequality and low power consumption. The LCD-applied portable televisionand notebook computer have been introduced in the market, but there areproblems to be solved in such LCD-applied devices. In particular, sizeand weight are important factors to be considered for the LCD.

[0007] For a small size and light LCD, there are several availablemethods for reducing the size and weight of the LCD element. However,the driving circuit and the thin film transistor, which are necessaryelements of the LCD, are so thin that reducing these elements will notaffect the weight in any significant manner. On the other hand, it ispossible to reduce the weight of the LCD element by reducing the weightof the glass substrate that is a basic element of the LCD. Specifically,since the glass substrate is a heavy element of the LCD, methods ofreducing the weight of the glass substrate have been continuouslyresearched.

[0008] For a glass substrate of a given surface area, a light glasssubstrate requires a thin glass substrate. However, known methods ofthinning the glass substrate cause damage including internalimperfections and surface roughness. Thus, the mechanical strength ofthe glass substrate is weakened, and the image quality of the LCD isaccordingly deteriorated.

[0009] Conventionally, the most common method of reducing the weight ofthe glass substrate is to etch the surface of the glass substrate bysoaking the substrate in a container having an etchant. In this method,however, the substrate is often not etched uniformly because of thenon-uniform surface of the substrate. Further, the impurities generatedduring the etching process often attach to the surface of the substrateso that the resulting surface becomes even rougher.

[0010] To solve the aforementioned problems, the substrate is placed ina container having an etchant and then bubbles are generated anddirected through a porous plate to the surface of the substrate in orderto remove the impurities attached to the surface of the substrate, and afresh etchant is applied to the surface of the substrate.

[0011]FIG. 1 is a sectional view showing a related art apparatus foretching a glass substrate that is etched in a method employing nitrogenbubbles.

[0012] For reference, the related art was filed by the Applicant of thepresent invention as U.S. patent application Ser. No. 09/389,959.Therefore, the present invention is an improvement of the related art.

[0013] As shown in FIG. 1, a teflon cassette 117 maintaining fixedspaces is formed in the interior of etching bath 111 filled with etchant121. The height of the etchant 121 is lower than that of the etchingbath 111 so that the etchant cannot flow out to the outside. In theteflon cassette 117, a substrate 119 including a color filter substrateand a thin film transistor (TFL) substrate is supported by a supportmeans (not shown in the figures). A nitrogen bubble generation pipe 113is formed on the lower portion of the teflon cassette 117 so thatnitrogen bubbles 123 are supplied through a plurality of the nitrogenbubble generation tubes 115. The supplied nitrogen bubbles 123 risealong the surface of the substrate 119 so that the impurities generatedduring the photolithography process and adhering to the substratesurface are removed. In this type of etching process, the extent ofetching of the substrate 119 depends on, and therefore can be determinedby, the temperature obtained from an exothermic reaction that isgenerated between the etchant 121 and the substrate 119.

[0014] In this related art method, however, since the bubbles,necessarily having different sizes, are applied on the upper portion andlower portion of the substrate, there is a resultant thicknessdifference between the upper portion and lower portion. As a result, thesubstrate is still easily damaged even by light force during the LCDprocess because of the non-uniformity of the thickness of the substrate.Further, the substrate must be soaked for a long period, for example,scores of minutes, to etch the substrate sufficiently. Thus, theprocessing cost is increased in this method.

SUMMARY OF THE INVENTION

[0015] Accordingly, the present invention is directed to an apparatusfor etching a glass substrate that substantially obviates one or moreproblems due to limitations and disadvantages of the related art.

[0016] An object of the present invention is to provide an apparatus foretching a glass substrate having a thin thickness and uniform surface.

[0017] To achieve the objects and in accordance with the purpose of theinvention, as embodied and broadly described herein, the apparatus foretching the glass substrate comprises an etching bath filled withetchant, a teflon cassette in the interior of the etching bath, saidteflon cassette supporting a substrate including a color filtersubstrate and a TFT substrate, and an ultrasonic oscillator generatingultrasonic vibration, attached to the exterior of the etching bath.

[0018] According to the present invention, impurities attached on theglass substrate can be removed during the etching process, before thephotolithography process and without a special impurity removal. Afterassembling a color filter substrate and TFT substrate, when a glasssubstrate is etched, impurities generated during the etching processattached on the surface of the glass substrate are removed so that thesurface of the glass substrate will be uniform.

[0019] It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory and are intended to provide further explanation of theinvention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are included to provide afurther understanding of the invention and are incorporated in andconstitute a part of the specification, illustrate embodiments of theinvention and together with the written description serve to explain theprinciples of the invention.

[0021] In the drawings:

[0022]FIG. 1 is a sectional view showing the apparatus for etching aglass substrate of the related art.

[0023]FIG. 2 is a sectional view showing the apparatus for etching aglass substrate according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, the apparatus for etching a glass substrate of thepresent invention is explained in detail by the accompanying drawings.

[0025]FIG. 2 is a sectional view showing the apparatus for etching aglass substrate according to the present invention. As shown in thefigure, the etching apparatus according to the present inventioncomprises an etching bath 211 filled with etchant 221, a teflon cassette217 in the interior of the etching bath 211, said cassette 217supporting a substrate 219 including a color filter substrate and a TFTsubstrate and an ultrasonic oscillator 223 that is generating ultrasonicvibration and is attached to the exterior of the etching bath 211, andwhich removes impurity by ultrasonic oscillation.

[0026] The height of the etchant 221 is lower than that of the etchingbath 211 so that the etchant 221 cannot flow out to the outside. Theetchant 221 is typically a hydrofluoric acid (HF) solution. Thesubstrate 219 including a color filter substrate and a TFT substrate issupported by a support means (not shown in the figures) maintainingfixed spaces.

[0027] Ultrasonic vibration (represented by dotted line arrows in thefigures) generated by the ultrasonic oscillator 223 removes impuritiesattached on the surface of the substrate 219, wherein a shock effectgenerated by the ultrasonic oscillation is provided on the surface ofthe substrate 219 so that the impurities originated fromphotolithography processes are removed from the surface of the substrate219.

[0028] Herein, the etching processes using the apparatus of the presentinvention for etching a glass substrate will be described.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0029] (1) The etching bath 211 is filled with etchant 221.

[0030] (2) The teflon cassette 217 supporting the assembled glasssubstrate 219 is completely submerged in the etchant 221.

[0031] (3) After the teflon cassette 217 is completely submerged in theetchant 221, an ultrasonic oscillator 223 is oscillated within 30seconds.

[0032] (4) In order to reduce operation time by heating effect, thetemperature of the etchant is raised about 5-10° C.

[0033] As previously known, the ultrasonic vibration used in the presentinvention is widely used in fish-detecting depth measurementapparatuses, cleaning apparatuses, ultrasonic process apparatuses, inthe medical and physical therapy field, and other end use technologies.In the present invention, the ultrasonic vibration separates theimpurities produced during photolithography processes from the surfaceof the substrate, and effectively removes the organic layer formed onthe surface of the substrate.

[0034] The method of removing impurities using nitrogen bubbles in therelated art has a problem generated by the nature of nitrogen bubbles.Also in the method, a bubble generator must be provided in the interiorof the etching bath because nitrogen bubbles have to pass the surface ofthe glass substrate. This structure provides many limitations in theselection of etchant and in the design of etching apparatus.

[0035] On the other hand, impurities can be separated from the surfaceof the substrate through ultrasonic oscillation without contactingdirectly on the glass substrate in the present invention. Therefore,maximum simplification of the etching apparatus is obtained.

[0036] In the case that the desired thickness of the substrate afteretching is very thin, the present invention can be prove more effective.That is, ultrasonic oscillation can be easily controlled mechanically,and the present invention can thereby prevent damage to the substrate,even when etching of long duration is necessary, as in the case ofproducing a very thin substrate.

[0037] Consequently, since the apparatus for etching a glass substrateof the present invention employs ultrasonic vibration in order to removefrom the glass substrate the impurities generated during thephotolithography process, a glass substrate is readily processed to havea uniformly thin thickness and a uniformly flat surface.

[0038] Also, simplicity of manufacturing processes is obtained becauseno special processes are needed before the photolithography processes toremove impurities attached on the surface of the glass substrate.

[0039] It will be apparent to those skilled in the art that variousmodifications can be made in the multi-domain liquid crystal displaydevice and method of manufacturing of the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. An apparatus for etching a glass substrate,comprising: an etching bath containing an etchant; a holder forsupporting said glass substrate in the etching bath; and an ultrasonicoscillator generating ultrasonic vibration on a surface of saidsubstrate.
 2. The apparatus for etching a glass substrate of claim 1,wherein said etchant comprises hydrofluoric acid.
 3. The apparatus foretching a glass substrate of claim 1, wherein said holder comprisesacid-resistant material.
 4. The apparatus for etching a glass substrateof claim 3, wherein said acid-resistant material comprisespolytetrafluoroethylene.
 5. The apparatus for etching a glass substrateof claim 1, further comprising a thermometer for measuring thetemperature of the etchant.
 6. The apparatus for etching a glasssubstrate of claim 1, further comprising a thermostat for signaling aspecific temperature rise of said etchant.
 7. The apparatus for etchinga glass substrate of claim 1, wherein said holder supports a pluralityof glass substrates.
 8. The apparatus for etching a glass substrate ofclaim 1, wherein said ultrasonic oscillator is located in an interior ofsaid etching bath.
 9. The apparatus for etching a glass substrate ofclaim 1, wherein said ultrasonic oscillator is located exterior to saidetching bath.
 10. The apparatus for etching a glass substrate of claim1, wherein said holder is located in an interior of said etching bath.11. An apparatus for etching a glass substrate, comprising: an etchingbath filled with an etchant; a holder for supporting said glasssubstrate in the etching bath; an ultrasonic oscillator generatingultrasonic vibration on a surface of said substrate; and a temperaturesensor installed in said etching bath.
 12. The apparatus for etching aglass substrate of claim 11, further comprising a control unit forreceiving a temperature indicating signal from said temperature sensorand generating an etching termination signal when the temperature signalindicates an etching termination temperature.
 13. The apparatus foretching a glass substrate of claim 12, wherein said control unitdetermines said etching termination temperature from said temperatureindicating signal.
 14. The apparatus for etching a glass substrate ofclaim 11, wherein said etchant comprises hydrofluoric acid.
 15. Theapparatus for etching a glass substrate of claim 11, wherein said holdercomprises acid-resistant material.
 16. The apparatus for etching a glasssubstrate of claim 15, wherein said acid-resistant material comprisespolytetrafluoroethylene.
 17. The apparatus for etching a glass substrateof claim 11, wherein said holder contains a plurality of glasssubstrates.
 18. The apparatus for etching a glass substrate of claim 11,wherein said ultrasonic oscillator is located in an interior of saidetching bath.
 19. The apparatus for etching a glass substrate of claim11, wherein said ultrasonic oscillator is located exterior to saidetching bath.
 20. The apparatus for etching a glass substrate of claim11, wherein said holder is located in an interior of said etching bath.21. The apparatus for etching a glass substrate of claim 11, furthercomprising an indicator for displaying the temperature monitored by saidtemperature sensor.